Steps to reproduce:
1. Start Matterhorn in a distributed setup, then stop it
2. Register a second DNS name for one of the hosts, change the hosts's server.url configuration to match that second name instead of the first one
3. Start Matterhorn again, the "Statistics" tab will now show one host as "offline"
Matterhorn will now keep saying that the "offline" host is back online, even though that's not true. The reason for this is that it is doing an HTTP OPTIONS request to that host, which is reachable through the second address, but still the host is not online, so the service registry will keep "discovering" that host.